Manufacture of pressed or filtered wood products



Patented Oct. 25, 1932 UNITED STATES PATENT ounce Q FRANCIS L. CARSON,0F *SAIT FRANCISCO, CALIFORNIA, A8SIGNOB T0 m PAGH'IG Eli LUMBERGQHPANY, OF SAN FRANCISCO, CALIFORNIA, A OOBFOBATIGH O1 a murao'runa orrnnssnn on rnxr woon rnonucrs I Ho Drawin n.

The present invention relates to the manufacture of pressed or filteredwood board, sheets and shapes, from wood which has been shredded and, bymechanical means, into hair-like fiber. This invention has particularreference to processes wherein soluble soaps are used in connection withvegetable starch and metallic compounds to produce artificial boards,mats, sheets and shapes, having the properties of resiliency,plasticity, low thermal conductivity, high tensile strength, resistanceto water, or moisture, as hereinafter more fully described.

l am aware that the specific raw materials which 1 use in my novelprocess have been used individually or in certain combination in thepaper making industry prior to my invention, but insofar as I am aware,they have never been used in the combination and for paper, which issubse uently extracted in the form of pulp from tie beater engine, ll amnot aware that it has been previously proposed to suspend raw shreddedhair-like wood, wood'bark, or other vegetable fiber, in a solution ofcolloidal starch and soap, which solution acts as a double medium ofconveying the fibers and cementing the fibers together to'produceartificial boards of high tensile strength and great resiliency, lowthermal conductivity and springiness.

Briefly stated, my inventioncomprises the manufacture of artificialboards, sheets and shapes from raw shredded wood, in which. process theindividual hair-like fibers are cemerited together by means of avegetable starch. These soaps are applied to the fibers in the form of asolution containing vegetable starch. The combined or cemented fibersare waterproofed by treating the same with aluminum sulphate or itsequivalent, whereby an insoluble metallic compound of the organic acidis produced on the matted fibers.

Shredded bark, such as that produced from these trees, commonly known asSequoia, is

' under the speci Application filed January 7, 1981. Serial Ho. 5077?.

ideal for my purpose. These trees are termed 0 names of Washingtonia andSam rvirons and are particular 3y native to alifornia, being mostlycalle redwood,

I have discovered that the bark of these trees lends itself admirably toa mechanical shredding action, whereby hair-like fiber is produced invarious lengths from a. maximum of three inches in length or longer to afiber in the form oif impalpable powder The hair-like fiber oi theredwood barlr mats readily when precipitated on a filterplate from'asolution of proper consistency, and this .material may be used togetherwith my binding agents, or may be used as a dilu cut and strengtheningfactor with other shredded woods which do not felt so readily,

The liquid binding agent, later described, acts as an ideal conveyingand fi tration medium for the shredded hair lilre which I describe.

Sodium and potassium, resinates, oleates and palmitates, are all plasticin character and are all water soluble, and materials formed with andcemented together by any of them will not hold shape under the action ofmoisture and temperature changes.

Wood and bark fibers, while they can be formed into mats or sheets byprecipitating the same on screens from suitable solutions are inthemselves, oil insuiiicient strength to be of commercial value unless asubstance of adhesive character is distributed throughout the body ofthe mats or sheets.

I find that vegetable starch hesive and also as a strengthening,toughen- 1n hZEP-like fibers of wood. In order to render the starchbinding medium water-proof,1 also provide an insoluble metallic soapwhich coats the starch on the fiber, with a moisture impervious film. Iwish to point out that the said insoluble metallic soap acts also as anassistant to the starch in its binding function.

It is well known by those skilled in the acts as an ad- 1 and stifieningfactor upon individual art that through chemical reaction, insolubleinto contact with metallic sulphates and the hke, for example: ficoHuogNa) 2A1;

ma reatnate+aluminum aul ate aluminum resinate sodium sulphate Also inlike manner, sulphates of metals react with tassium resinate and withthe into the solution containing the pulp and immediately thereafter,introduce alum to cause a reaction by precipitation of the insolublematerial upon the pulp fiber. As a consequence, the entire conveyingliquid solution becomes waste and the disposal problem 1s m co uencegreat and costly. In order to dispense with the large waste waterproblem, I have devised a method whereby the raw fibers are conve ed tothe screen of the board forming mac ine. The conveying solution comrises soluble soap and starch, and this so ution is recovered frombeneath the screen of the board forming machine and re-used in theprocess. a subsequent ste I treat the moist mat on the screen with an umsolution and recover the surplus alum solution as in the case of theconveying solution. While this alum solution is depleted in alum andcontaminated with impurities nevertheless the loss of alum .may be relaced by freshly added quantities of the sai alum and the impurities aresuch that no precipitation occurs until it has been re-psed aboutseventeen times. At this mt, the solution, by sim le concentration ofthe old alum solution, will render the recove of sodium sulphatepossible.

I ave discovered that it is poflble to precipitate the insoluble plasticmetallic soaps upon the hair-like fiber, making up my sheet or boardafter all surplus liquid has been filteredtherefrom. By surplus I meanall the conveying solution which does not adhere to the air-like fiberof the mat after filtration. I have discovered that a mat or sheet,having been formed by felting from a solution of water, soluble soa andcolloidal or semicolloidal starch-and eft in a condition of a saturatedmat upon the screen uponwhich 1t has been filtered, may then besubjected to the additional chemical reaction of renderingthe containedbinder insoluble in water in the following manner:

- A solution of alum in water or. a solution of alum in a colloidalstarch solution may be filtered through the mat, and the .sbluble soapcoating of each individual hair-like fiber is converted to an insolubleplaster or metallic soap thereon. renders the 1,ss4,toa

se arate hair-like particles of the mat upon su quent drying of themoisture therefrom, hi hly moisture resistant.

have discovered that mats or sheets such as I have described above arelow in thermal conductivity and resilient to applied pressure, in thatbeing slightly compressed and the pressure removed, the mats expand tothe ori inal volume occupied.

-In' t e following specific examples the method of pre aring the stockfrom which the artifical boar s, sheets or shapes are made,

is described. However, it is to be distinctly understood that I do notlimit myself to the specific proportions set forth therein since myinvention is of broad scope and the following examples are merelyillustrative of a large number of modifications falling within the scopeof the present invention. The parts are by weight.

Example I I makev up a solution of water, sodium oleate, and starch, ina colloidal or semicolloidal condition. The percentages are: Water "92parts by weight. Sodium resinate 5 parts by weight. Corn starch 3 poundsby weight.

fiber into 100 pounds of the foregoing mixture of soap and starchsolutions and thoroughly mix the same to distribute the fibersthroughout the entire colloidal mass. The thoroughly mixed mass is runonto a screen where the excess liquid drains ofi, or is sucked oil byvacuum or forcing it through by an air or steam blast, leaving the matof wood hairlike fibers saturated with the soap and starch solution. Ithen prepare a solution of aluminum sulphate by dissolving 1.6 ounces ofsalt in ten pounds of water. I then ur this solution on the saturatedmat eacribed above. However, it is preferable to introduce the alumsolution onto the mat by means of a porous continuous belt disposedabove the screen on two or more rolls, and adapted to contact the saidmat. These "rolls are adapted'to move toward and from the screen." Thisarrangement of rolls and continuous belt provides means for supplyingthe mat with the alum solution at a low velocity, thereby preventingdisruption of the mat. 'lhe alunausea I dissolve eight pounds of sodiumresinate in water and make the solution up to one hundred pounds. In aseparate container I make up a starch paste as in Example I, such thatthe solution contains 4 pounds of corn starch in 100 pounds of water.The solutions are combined as in Example I, and I introduce-into themixture about fifteen pounds of shredded redwood bark which has a fiberlength of about one-half inch. I form a mat or sheet from this solutionand waterproof the hair-like fiber the same as in Examplel. It ispointed out that the amount of soap may vary from one-half to twenty percent of the combined solutions into which the shredded fibers areintroduced. The amount of starch may vary from one-half to ten per cent.The amount used will depend on the degree of density and stiffnessrequired in the final product and. the mechanical compression, if any,to which the filtered mat or sheet may be subsequently subjected.

'the moisture-proofed mat or sheet is dried and the product obtainedaccording to Example l is resilient andspringy, while that obtained bythe procedure of Example H is by comparison, stiff and rigid and hasconsiderable strength. Both products are extremely light in weight andare stable. The denser product made by Example ll weighs about tenpounds per cubic foothas a thermal conductivity of 0.28 B. t. 11. perone inch of thick ness per degree Fahrenheit difference in temperaturebetween the two sides (hot plate method) it will be readily understoodby those skilled in the art that the process oi forming sheets or matsfrom the solution as outlinedv above, can lie-readily accomplished in avariety of ways. Almost any of the board making machines now on themarket will lend itself to the expeditious and economical handling ofthis solutionand the production 0? the finished product.

As to the roduct (sheet or mat) filtered j from the solution as shown,by heating the mat containing aluminum resinate up to a uniformtemperature of 250 Fahrenheit, and compressing the same under themechanical action of rolls or resses. or both, I am able to formtherefrom a stifi, rigid, dense product of high resistance to impact,abrasion, tension and compression, water resistant and with extremelysmooth surfaces, which is also capable of receiving applied finishes.This product has all the advantages of pressed wood pulp boards whilebeing extremely inexpensive to produce. The preferred pressure is 400pounds per square inch.

As used inthe present specification and claims by the term .raw fibers,I mean vegstable fibers which have not been subjected to a ueous orchemical digestion or treatmen 0 any kind. i

What I claim is 1. The process of producing fibrous boards, sheets orshapes which comprises introducing shredded raw vegetable fi ers into asolution containing soap and starch and forming a board, sheet or shapeof any'desired thickness.

2. The process of producing fibrous board's,

- sheets or shapes WhlChCOmPIISBS introducing shredded raw fibers into asolution containing an alkaline metal resinate and starch forming a.bpard, sheet or shape of any desired thickness.

3. The process of producing fibrous boards,

sheets or shapes which comprises introducing shredded raw redwood fibersinto a solution containing sodium resinate and starch and forming aboard, sheet or shape of any desired thickness. v

4. The process of producing fibrous boards, sheets or shapes whichcomprises introducing raw shredded wood fibers into a solutioncontaining an alkaline metal salt of a resin acid and forming a board,sheet or shape of any desired thickness.

5. 'l he process of producing fibrous boards, sheets or shapes whichcompmses introducing raw shredded redwood bark into a solutioncontaining sodium resinate and starch and forming a board, sheet orshape of any desired thickness.

6. As a new article oi manufacture, a unitary structure comprisingshredded raw vegetable fibers cemented together by means of starch.

7. As a new article of manufacture, a board comprising shredded rawfibers cemented together by means of starch and a soap.

8. As a new article of manufacture, a sheet comprising shredded rawvegetable fibers cemented together by means of soap.

9. As a new article of manufacture, a unitary structure comprisingshredded raw Vegstable fibers cemented together by means of starch andcontaining an insoluble soap distributed throughout the mass.

10. As a new article of manufacture, a board comprising shredded rawvegetable fibers cemented together by means of a starch and containingsoap distributed throughout the mass.

11. As a new article of manufacture, a resilient board comprisingshredded redwood bark cemented together by means of starch andcontaining soap distributed throughout the mass.

12. As a new article of manufacture, a

water-resistant resilient board comprising redwood bark fiber, producedby shredding and having a length of approximately three inches, cementedtogether by means of and having aluminum resinate distributed throughoutthe entire mass.

13. As an article of manufacture, a water resistant resilient boardcomprisin raw redwood bark fiber produced by shre ding and havingalength up to three inches cemented together by means of starch andwaterproofed by aluminum resinate.

14. As a new article of manufacture a pressed board comprising rawvegetable fiber cemented together by means of starch and containing soapdistributed throughout the mass, the-said board having been compressedat a pressure of approximately 400 pounds and a temperature of 250 F.

15. The process of producing fibrous boards, sheets or shapes,comprising introducing shredded raw vegetable fibers into a solutioncontaining soap and starch, forming a board, sheet or shape, recoveringfor re-use the excess solution, introducing an alum solution on theformed board, sheet or shape while in a moist state and recovering thissolution for re-use.

16. In the process of producing fibrous boards, sheets or shapes fromraw vegetable fibers, the step of recovering for re-use depleted alumsolution.

In testimony whereof I afiix my si ature.

' FRANCIS L. CAR ON.

